Correct answer - "Use AWS Lambda aliases" : By default, an alias points to a single Lambda
function version. When the alias is updated to point to a different function version, incoming
request traffic in turn instantly points to the updated version. This exposes that alias to any
potential instabilities introduced by the new version. To minimize this impact, you can
implement the routing-config parameter of the Lambda alias that allows you to point to two
different versions of the Lambda function and dictate what percentage of incoming traffic is
sent to each version.
Incorrect:
"Use environment variables" - Environment variables for Lambda functions enable you to
dynamically pass settings to your function code and libraries, without making changes to your
code
"Use Route 53" - Unfortunately Route 53 cannot shift traffic between Lambda versions and is
better served shifting internet traffic
"Deploy your Lambda in a VPC" - Configuring a VPC is more for security purposes